1. Field of the Invention
The present invention relates to needle wire localizers for marking lesion locations within a body using a probe wire that is slidably received in a cannula needle and, more particularly, is directed toward a locking and positioning device for a needle wire localizer that constrains and precisely positions a probe wire relative to the cannula needle.
2. Description of the Prior Art
It is known to rely on mammography in conjunction with a cannula needle having a probe wire therein for localization of a presymptomatic, non-palpable breast lesion. In such a procedure, a cannula needle having a wire sheathed therein is inserted so that the pointed end of the needle is located in the tissue area of pathological alteration, preferably, less than 2 cm from the lesion. A mammogram is taken to confirm the probe position. If the probe is not positioned close to the lesion, then the probe is relocated, or an additional probe is inserted, and a further mammogram is taken. When the probe location is acceptable, the cannula needle is taped to the patient and the patient transferred to surgery for lesion excision.
U.S. Pat. No. 4,616,656 and the references cited therein show various medical devices for inserting wires into patients. U.S. Pat. No. 4,616,656 discloses a self-actuating breast lesion probe which utilizes a memory alloy probe wire having a J-bend at its pointed or working end. The probe wire is slidably received within a cannula needle and a locking device having a clamping screw is used to clamp the wire. The end of the screw bears against the wire and prevents it from moving relative to the needle. The locking device of this patent suffers from the disadvantage that the screw causes an undesirable bend in the wire.